Method and device for transporting heat energy that is produced in a motor vehicle

ABSTRACT

A method and an apparatus for transporting thermal energy produced in a motor vehicle provides that the waste heat of an electronic component ( 42 ), such as a pulse-controlled inverter, be utilized to heat other vehicle parts, such as the internal combustion engine ( 12 ) or the passenger compartment. To that end, preferably two coolant circuits ( 10, 40 ) are provided, which can be coupled to one another or decoupled from another in order to control the flow of heat.

PRIOR ART

The invention relates to a method and an apparatus for transportingthermal energy produced in a motor vehicle.

Until now, the energy produced in vehicle parts in their operationmostly goes unused and is emitted without being controlled to theenvironment. Only in the case of the internal combustion engine is thethermal energy contained in its coolant circuit utilized to heat thepassenger compartment, via a heating-type heat exchanger.

The object of the invention is to create a method and an apparatus bymeans of which the thermal energy produced in operation of the motorvehicle is utilized in such a way as to reduce the energy consumption ofthe motor vehicle.

ADVANTAGES OF THE INVENTION

This is attained by a method that is characterized by the follow steps:

an electronic component in the motor vehicle is cooled, and

the thermal energy dissipated upon cooling of the component is conductedonward to some other vehicle part to heat it.

The invention is furthermore attained by an apparatus which serves inparticular to perform the method of the invention. The apparatus has anelectronic component, which is coupled with a heat-dissipating line, andthe line in turn is coupled to another vehicle part in such a way thatthermal energy from the component is output to the vehicle part via theline.

In particular, the invention is employed to dissipate the thermal energyfrom so-called power electronics, that is, electronics characterized byhigh electrical consumption.

The invention is based on the recognition that the waste heat producedin the operation of electronic components has until now been completelyunutilized in the motor vehicle and simply output to the ambient air.The power and number of electronic components and thus the quantity ofheat to be dissipated from electronic components is increasing from onemotor vehicle generation to the next. Furthermore, however, parts in themotor vehicle, and here the term “parts” is not meant to be limited to asingle part but instead to cover entire structural groups, are providedthat require heat for their desired operation. While in the case ofelectronic components on the one hand, such applications as large-areacooling fins are provided for dissipating thermal energy to the ambientair, on the other, additional measures are taken to heat other vehicleparts. For instance, because of the increasing efficiency of internalcombustion engines, to achieve a high level of heating comfort in dieselvehicles, it has meanwhile become necessary to provide supplementaryelectric heaters to heat the passenger compartment, but as a result bothelectrical and fuel consumption rise. Because of the higher demand forelectrical energy in a motor vehicle, for instance, in future a 42-voltstarter generator will be employed, whose power electronics, such as thepulse-controlled inverter, might have a heat loss of more than onekilowatt. By means of the invention, this energy could for instance becarried into the coolant circuit of the engine or directly into aheating-type heat exchanger for heating the passenger compartment.

Advantageous features of the invention will become apparent from thedependent claims.

Preferably, the dissipated thermal energy from the electronic componentis conducted onward in controlled fashion to the vehicle part to beheated; that is, the quantity of heat supplied to the vehicle part iscontrolled, for instance in order to prevent the vehicle part frombecoming overheated or to adjust it to its optimal temperature.

In a preferred embodiment, the coolant circuit of the component isassigned its own radiator. As a function of a predetermined allowable ordesired maximum temperature of the component and/or a predeterminedlimit temperature of the vehicle part to be heated, the coolant circuitof the component is coupled to that of the vehicle part and/or to itsown radiator. Situations are conceivable in which the dissipation of thethermal energy from the electronic component to the structural part tobe heated is not sufficient to cool the component adequately. Then itsown radiator must be turned on, by way of which thermal energy is outputfor instance to the environment. Furthermore, the vehicle part to beheated can also have an optimal temperature range that should not beexceeded or undershot, if performance is to be maintained. For instance,once an internal combustion engine has reached its optimal operatingtemperature, it should not be cooled down. However, if the temperatureof a coolant, supplied from the coolant circuit of the component intothe coolant circuit of the engine, were below the desired temperature inthe coolant circuit of the engine, then coupling the two coolantcircuits to one another would lead to an undesired additional cooling ofthe engine. Conversely, however, the radiator of the coolant circuitassigned to the component should be turned off if the engine has not yetreached its operating temperature. Specifically, then as much heat aspossible should be supplied from the component to the coolant circuit ofthe engine, so that the latter will reach its optimal operatingtemperature as fast as possible.

To attain the aforementioned goals, it is also advantageous that thecoolant circuits of the component and of the engine are decoupled fromone another, and that preferably in addition the coolant circuit of thecomponent supplies thermal energy to its own radiator, whenever the exittemperature of the coolant from the coolant circuit of the component isbelow a predetermined operating temperature of the engine, which theengine has just reached at that moment.

Furthermore, in one feature, the invention provides that the volumetricflow of coolant in at least one of the two coolant circuits becontrolled as needed via at least one electric coolant pump integratedwith the coolant circuit. Until now, mechanical pumps that are coupledwith the engine have been used as coolant pumps. For optimal adaptationof the heat transport in a coolant circuit, however, an electric coolantpump is now preferably used, by which the heat transport is possiblewith precision and as needed inside the coolant circuit or betweencircuits that are coupled with one another.

In one feature, the volumetric flow in the coolant circuit of the engineis controlled as a function of the engine temperature and the load rangeof the engine in which the engine is at that moment.

The method of the invention is also employed when the engine is turnedoff, for instance in order to utilize the energy of the still-warmcomponent to heat the passenger compartment.

The method of the invention is attractive particularly for hybridengines, in which the internal combustion engine is frequently off, andin the meantime electric motors or other electronic components are inoperation and produce heat.

The apparatus of the invention, in one feature, provides that theheat-dissipating line is part of a coolant circuit assigned to thecomponent, which coolant circuit communicates with the coolant circuitof the engine. The coolant circuit of the component can furthermore alsocommunicate directly with the heating-type heat exchanger, however, orcan have its own heating-type heat exchanger. In these versions, usingthe heat of the component to heat the passenger compartment is a primarygoal.

The coolant circuits of the component and of the engine can preferablybe coupled to one another and decoupled again from one another, toachieve control of the heat transport.

To avoid the energy loss in heat exchangers, the coolant circuits of thecomponent and of the engine preferably communicate in such a way thatcoolant from one coolant circuit can flow into that of the other; thatis, fluidically, the coolant circuits partly merge with one another.

DRAWINGS

Further characteristics and advantages of the invention will becomeapparent from the ensuing description and in conjunction with theensuing drawings. Shown in the drawings are:

FIG. 1, a block circuit diagram of a coolant circuit of an internalcombustion engine of the prior art;

FIG. 2, a block circuit diagram of a first embodiment of the apparatusof the invention for performing the method of the invention;

FIG. 3, a block circuit diagram of a second embodiment of the apparatusof the invention for performing the method of the invention; and

FIG. 4, a block circuit diagram of a third embodiment of the apparatusof the invention for performing the method of the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows a known coolant circuit 10 of an internal combustion engine12 of a motor vehicle. From the engine 12, a line 14 leads from thecoolant circuit 10 to a thermostat valve 16. From the thermostat valve16, a line 18 branches off to a radiator 20, and a line 22 branches offto a connecting line 24 between a radiator 20 and a mechanical coolantpump 26 coupled to the engine 12. The coolant pump 26 in turncommunicates fluidically with the engine 12. From the engine 12, a line28 branches off to a heating-type heat exchanger 30, which is used toheat the passenger compartment. On the outlet side, a line 32 connectsthe heating-type heat exchanger 30 to the connecting line 24.

At coolant temperatures below approximately 90° C., the thermostat valve16 allows only one flow line of the coolant, arriving via the line 14,via the line 22 to the connecting line 24. If the coolant temperatureexceeds 90° C., however, the thermostat valve 26 opens the circuittoward the radiator 20 and at the same time closes the line 22.

As FIG. 2 shows, the coolant circuit 40 of an electronic component 42,for instance in the form of a pulse-controlled inverter for a 42-voltstarter generator (not shown), is also integrated into the conventionalcoolant circuit, shown in FIG. 1, of the engine 12. All the partsalready described in conjunction with FIG. 1 are identified with thesame reference numerals in FIGS. 2-4 as well, where they are identicalto or have the same function or are used in the same way in otherembodiments. The coolant circuit 40 of the electronic component 42 canbe coupled to and decoupled from the coolant circuit 10 of the engine.The coolant circuit 40 of the component 42 includes a plurality oflines, which will now be explained.

One line 44 fluidically connects the component 42 to the connecting line24 in the coolant circuit 10, so that the coolant in the line 44 flowsinto the coolant circuit 10. The part of the connecting line 24downstream of the discharge point into the line 44, the mechanicalcoolant pump 26, the engine 12 (or more precisely, the lines carryingcoolant that are provided in the engine block) and an upstream part ofthe line 14 are each at the same time a component part of the coolantcircuit 40. Finally, a line 46 branches off from the line 14 and leadsto a 3-way valve 48. From the line 46, a line 50 also branches off to aradiator 52 assigned to the coolant circuit 40. On the outlet side, theradiator 52 communicates with the 3-way valve 48 via a line 54. The3-way valve 48 communicates in turn on the outlet side to the component42 via the line 56, as a result of which the coolant circuit 40 isclosed. A temperature sensor 58, which ascertains the temperature of thecoolant at this point, is seated in the line 56.

The apparatus shown in FIG. 2 and formed of two coolant circuits 10, 40that can be coupled together serve to transport thermal energy producedin a motor vehicle. For example, the apparatus is part of a hybrid motorvehicle, which has an electrical drive system and an internal combustionengine. When the vehicle is started, for instance on startup with anelectrical drive system, the power electronics represented by thecomponent 42 heat up so severely that they can have a heat loss of morethan 1 kW. This thermal energy is used to heat other vehicle parts,which in the present case are not merely a single part but rather anentire structural group in the form of the coolant circuit 10, as willbe explained below.

The waste heat from the component 42 is fed via coolant and the line 44into the coolant circuit 10, where immediately after starting of themotor vehicle it is used to heat the engine 12 quickly. On the engineoutput side, a partial volumetric flow of the coolant located in theline 14 is branched off and reaches the line 46. The temperature sensor58 ascertains the temperature immediately upstream the component 42. Ifthe coolant is cold enough, the valve 46 switches an appropriateopening, so that the line 46 communicates directly with the line 56, andthe branched-off coolant flows directly to the component 42. In thisway, all the waste heat from the component 42 is fed into the coolantcircuit 10.

If the temperature ascertained in the temperature sensor 58 is above apredetermined allowable maximum temperature for the electroniccomponent, the valve 48 is switched differently, so that all or some ofthe coolant located in the line 46 travels via the line 50 to reach theradiator 52, where it is cooled, and finally flows via the lines 54 and56 to the component 42.

A disadvantage of this version can occur whenever the temperature of thecoolant immediately downstream of the component 42 is below apredetermined limit temperature for the entry of the coolant into thecoolant circuit 10. This would in fact cause undesired cooling of theengine 12, if the engine has already reached its desired operatingtemperature.

One advantage of the embodiment shown in FIG. 2, however, is that thequantity of thermal energy that is fed into the coolant circuit 10 canbe controlled as needed by the valve 48.

Still more-precise control, more suitable to the demand, can be attainedby means of the embodiment of the apparatus shown in FIG. 3.

The apparatus shown in FIG. 3 makes it possible to decouple the coolantcircuits 10 and 40 completely from one another. To that end, instead ofthe line 44, a line 62 is extended from the component 42 directly to theradiator 52. From the line 62, a line 64 branches off to the connectingline 24, and a valve 66 is seated in the line 64. As a furtherdistinction from the embodiment of FIG. 2, there is no provision fordirect communication of the line 46 with the radiator 52. Furthermore,an electric coolant pump 68, which can precisely control the volumetricflow of coolant in the coolant circuit 40, is disposed in the line 56.The valves 48, 66 form a device for coupling and decoupling the coolantcircuits 10, 40.

The apparatus shown in FIG. 3 operates by the following method: As longas the coolant is at a low temperature, measured by the temperaturesensor 58, it flows out of the coolant circuit 10 via the line 46directly into the line 56, via the suitably switched valve 48. The valve66 is likewise open, so that some of the arriving flow reaches thecoolant circuit 10, and some reaches the radiator 52. However, if thetemperature of the coolant rises to excessively high values, then thevalve 48 is switched in such a way as to prevent the inflow of fluid viathe line 46. Instead, the lines 54 and 56 are made to communicate withone another. The valve 66 is closed, so that the coolant circuit 40 iscompletely decoupled from the coolant circuit 10, and the coolant canflow via the line 62 directly into the radiator 52 and from there viathe line 54 and the line 56 to the component 42, which it cools. Thecoolant flow for cooling the component 42 is now recirculated solely viathe electronic coolant pump 68. The coolant pump 68 can also be turnedon when both coolant circuits 10, 40 are coupled to one another, becausein this way the volumetric flow of coolant that cools the component 42can be supplied as needed and precisely metered to the coolant circuit10, and the volumetric flow is no longer dependent on the engine rpm.With the aid of the coolant pump 68, the component 42 can also be cooledwhen the engine 12 is off.

In the embodiment of the apparatus shown in FIG. 4, the quantity of heatsupplied to the coolant circuit 10 and the transport of heat within bothcoolant circuits 10, 40 can be controlled even more exactly. The layoutof this apparatus is largely identical to that shown in FIG. 3. However,instead of a mechanical coolant pump 26, an electric coolant pump 126 isprovided, which controls the volumetric flow 10 inside the coolantcircuit 10 exactly. Instead of the thermostat valve 14, a valve 116 thatcan be triggered from outside is provided. A thermostat valve leads to avery high pressure loss, so that the electric coolant pumps would haveto have high performance. Other designs of 3-way valves aredistinguished by a very low pressure loss, so that the pressure lossesin the coolant circuit 10 can be reduced. Furthermore, a valve 130 ispreferably also disposed downstream of the heating-type heat exchanger30.

To reduce fuel consumption in the partial-load range of the engine 12,the maximum allowable limit temperature in the coolant circuit 10 ishigher than in the conventional coolant circuits previously used. Toenable exact control of the temperatures in the entire apparatus and tosupply thermal energy to those points of the apparatus that require theenergy just at that time, the valves 116 and 130 and the electriccoolant pump 126 are all provided. For instance, if no heat isdissipated in the heating-type heat exchanger 30, then the valve 130 canprevent a flow of coolant through the lines 28 and 32, so that thecoolant circuit 10 is reduced in size. As needed, the quantity ofcoolant supplied to the engine can then be controlled, so that theengine can either be heated up fast or cooled fast.

Increasing the maximum allowable coolant temperature in the partial-loadrange of the engine 12 makes it possible to reduce fuel consumption. Inpartial-load operation, in the embodiment of FIG. 4, a coolanttemperature of about 110° C., for instance, is allowed, which reducesthe viscosity of the engine lubricant, as a result of which in turnconsumption can be additionally reduced. Still higher temperatures arenot sought, however, because otherwise the lubricant film could tear.The elevated allowable temperatures in the coolant circuit 10 can,however, lead to a thermal overload on the component 42, and thereforethe coolant circuit 40 can optionally be decoupled from the coolantcircuit 10 by way of suitable triggering of the valves 48 and 66.

An appropriate elevation of the temperature in the coolant circuit 10 inpartial-load operation is possible in the embodiment shown in FIG. 3 aswell.

Instead of the embodiments shown, it is also possible to assign thecoolant circuit 40 its own heating-type heat exchanger, so that whilethen the engine 12 can no longer be heated, in return the passengercompartment is heated without heat losses.

Coupling the two coolant circuits 10, 40 inside one common radiator,which then acts as a heat exchanger, is furthermore conceivable.

The invention is not limited to utilizing the energy that is generatedin a pulse-controlled inverter for a starter generator. This is merelyone preferred exemplary embodiment. Another example for the so-calledpower electronics whose energy is utilized is an electric motor of ahybrid vehicle, which has a plurality of electric motors to drive it.One electric motor then serves to start the vehicle or run it up tospeed, for instance, and is only briefly, but then very severely, underload. Then, the heat generated in the briefest time in the electricmotor can be utilized as well.

List of Reference Numerals

10: Coolant circuit of the internal combustion engine

12: Internal combustion engine

14: Line

16: Thermostat valve

18: Line

20: Radiator

22: Line

24: Connecting line

26: Mechanical coolant pump

28: Line

30: Heating heat exchanger

32: Line

40: Coolant circuit of the component

42: Electronic component

44: Line

46: Line

48: 3-way valve

50: Line

52: Radiator

54: Line

56: Line

58: Temperature sensor

62: Line

64: Line

66: Valve

68: Electric coolant pump

116: Triggerable valve

126: Electric coolant pump

130: Valve

What is claimed is:
 1. A method for transporting thermal energy producedin a motor vehicle having an engine (12) with a coolant circuit (10),characterized by the following steps: cooling of an electronic component(42) in the motor vehicle, and conducting the thermal energy, dissipatedupon cooling of the component (42), onward to another vehicle part toheat it, controlling volumetric flow in the coolant circuit (10) of theengine (12) as a function of the engine temperature and the load rangeof the engine (12) in which the engine is at that moment, at least onecoolant circuit (40) for the electronic component (42) is provided byway of which the heat is output to a coolant circuit (10) of an internalcombustion engine (12) of the vehicle or Is supplied to the passengercompartment, the electronic component (42) Is assigned a coolant circuit(40) with its own radiator (52), as a function of a predeterminedallowable maximum temperature of the component (42) and a predeterminedlimit temperature of the vehicle part to be heated, the coolant circuit(40) of the component (42) is coupled to the coolant circuit (10) of thevehicle part and/or to its own radiator (52), and the radiator (52) ofthe electronic component (42) is cooling the electronic component incase of insufficient heat transfer to the vehicle part.
 2. The method ofclaim 1, characterized in that the energy quantity supplied to thevehicle part to be heated is controlled.
 3. The method of claim 1,characterized in that as a function of the temperature of the vehiclepart to be heated and of the electronic component (42), the supply ofheat to the vehicle part to be heated is interrupted.
 4. The method ofclaim 1, characterized in that the coolant circuits (40, 10) of thecomponent (42) and of the engine (12) are decoupled from one anotherwhenever the coolant circuit (40) of the component (42) would lead tocooling of the engine (12).
 5. The method of claim 4, characterized inthat the coolant circuit (40) of the component (42) feeds thermal energyto its own radiator (52) whenever the coolant circuit (40) of thecomponent (42) would lead to cooling of the engine (12).
 6. The methodof claim 1, characterized in that the volumetric flow of coolant in atleast one of the two coolant circuits (10, 40) is controlled as neededvia at least one electric coolant pump (68; 126) integrated with thecoolant circuit (10, 40).
 7. The method of claim 1, characterized inthat it is employed with the engine (12) turned off.
 8. An apparatus fortransporting thermal energy produced in a motor vehicle, in particularfor performing the method of one of the foregoing claims, characterizedin that an electronic component (42) is coupled to a heat-dissipatingline (44; 62, 64), and the line (44; 62, 64) is re-coupled to anothervehicle part in such a way that thermal energy from the component (42)is output to the vehicle part via the line (44; 62, 64); and the line(44; 62, 64) is part of a coolant circuit (40) assigned to the component(42), which coolant circuit communicates with the coolant circuit (10)of an internal combustion engine (12) or a heating-type heat exchanger(30).
 9. The apparatus of claim 8, characterized in that the coolantcircuits (10, 40) can be coupled to one another and decoupled fromanother by means of a device.
 10. The apparatus of claim 8,characterized in that the coolant circuits (10, 40) communicate with oneanother in such a way that coolant from one coolant circuit (10, 40) canflow into the other coolant circuit (10, 40).
 11. The apparatus of claim8, characterized in that each coolant circuit (10, 40) is assigned itsown radiator (20, 52) that can be turned on selectively.
 12. Theapparatus of claim 8, characterized in that at least one electriccoolant pump (68, 126) is provided in at least one coolant circuit (40,10).
 13. The apparatus of claim 8, characterized in that a heating-typeheat exchanger (30) for heating the passenger compartment is provided inat least one of the coolant circuits (10, 40).
 14. An apparatus fortransporting thermal energy produced in a motor vehicle, in particularfor performing the method of one of the foregoing claims, characterizedin that an electronic component (42) is coupled to a heat-dissipatingline (44; 62, 64), and the line (44; 62, 64) is re-coupled to anothervehicle part in such a way that thermal energy from the component (42)is output to the vehicle part via the line (44; 62, 64); and theelectronic component (42) is a pulse-controlled inverter for a startergenerator.
 15. A method for transporting thermal energy produced in amotor vehicle having an engine (12) with a coolant circuit (10),characterized by the following steps: cooling of an electronic component(42) in the motor vehicle, and conducting the thermal energy, dissipatedupon cooling of the component (42), onward to another vehicle part toheat it, providing at least one coolant circuit (40) for the electroniccomponent (42), by way of which the heat is output to a coolant circuit(10) of an internal combustion engine (12) of the vehicle or is suppliedto the passenger compartment, controlling the volumetric flow of coolantin at least one of the two coolant circuits (10, 40) as needed via atleast one electric coolant pump (68; 126) integrated with the coolantcircuit (10, 40), controlling volumetric flow in the coolant circuit(10) of the engine (12) as a function of the engine temperature and theload range of the engine (12) in which the engine is at that moment, andcontrolling the volumetric flow of both said coolant circuits (10, 40)by associated electronic coolant pumps.